1. Field of the Invention
This invention relates to electronic systems, and more particularly, to the detection of temperatures in an integrated circuit.
2. Description of the Related Art
One of the problems that must be dealt with in the design of electronic systems is the generation of heat. Integrated circuits (IC's) are a source of a significant portion of the heat generated by electronic circuits. Thus, many IC's include one or more temperature sensors to allow the monitoring of the temperature of the IC die during operation. Various mechanisms may be used with temperature sensors to reduce or cut off power to an IC when its temperature reaches a critical point that above which damage might occur.
Some IC's may require multiple temperature sensors. This is due to the fact that many of these IC's do not generate heat evenly. Some portions of the silicon die may include a higher circuit density than other areas, and thus may generate more heat than other less dense areas. The type of circuitry on various portions of a silicon die may also affect heat generation. For example, a portion of an IC including static memory that is not frequently accessed may generate less heat than arithmetic circuitry that is frequently used. Thus, temperature sensors may be placed at various points on the die according to the amount of heat generated by circuitry in the general vicinity.
Determining the placement of temperature sensors may not always be a straightforward issue. Circuit density in some areas where temperature sensors are necessary may limit placement options. For example, the number and placement of temperature sensors in a processor core may be constrained by the core's circuit density. Another consideration that may limit the placement of temperature sensors is the routing of signals, particularly in dense areas such as a processor core. The amount of area consumed by each temperature sensor circuit may further constrain both the number of temperature sensors employed as well as their placement within a circuit. Thus, limits on the number of temperature sensing circuits and the placement of each may in turn reduce the effectiveness of the overall temperature sensing system. Power supply considerations may be another limiting factor, as power supply voltages most suitable for certain types of sensors (e.g., analog power supplies for analog temperature sensors) may be unavailable in a given processor core.